Substituted 2-beta-acetanilidovinyl benzoxazoles and method of preparation



Patented Oct. 14, 1947 SUBSTITUTED 2 BENZOXAZOLES PREPARATION ,8 ACETANILIDOVINY L Alfred W. Anish, Johnson City, N.

N Drawing. Application March I Serial No. 525,937

I: 1.1 a] f j mass, 3 (01. 260-301) inventionyre dtd e: com, to eased the benzoxazole class and their mQthQdZQfJ prenata- More specifically, my,- inyentien -relates; to; 2-5- acetanilidovinyl-benzoxazole contain as a substituent in the aryl nucleusdsomeric;(secondary and tertiary) alkyl or aryl-alkyl groups. My new compounds may, be used as intermediates in the production of new .oxacarbocyanine dyes which are particularly useful in sensitizing photographic emulsions. Such dyes made from my novel benzoxazole intermediates are characterized by a steep cut-off in the spectral curve. Such characteristics are highly desirable, especially in sensitizing dyes used in color photography emulsions, where it is desirable that the multi-layer emulsions be sensitiye; to. certain ranges of wave lengths; i

My novel comp un s may .renresented sby the following structuralfornmla;

' In the above formula R. representsan, isomeric (secondary and tertiary) alkyl or aryl-alky1 g oup, such as isobuty c l, amyl,. tertiary hexyl, isopropyl, diisobutyl, 2.- or. 3-methyli-buty1 groups. The radical may be sub stituted in any position in the benzene nucleus. Generally the 5 and 6 positions are preferred. R1 representsianalkyl, alkoxyal'kyl, aryl or aralkyl group, such as, for example, methyl,ethyl, 3- ethOJ ethyLjbutyI, allyl or benzyl, and Xrepre sents an'anion. 1

In general, the. intermediates may "be prepared by' first nitratinga phenol whichis substituted in the benzene nucleus by a secondaryortertiary alkyl or aryl-alkyl' radical. LSucgh nitro phenols. may be prepared according to the process'oi Patent- No. 2,207,727. The nitro-compound isoamyl, tertiary I then react any suitable quaternary ammonium salt of the secondary and tertiary substituted benzoxazole-so obtained, such. as the ethiod-idawithdiphenyliormamidine in the presence of acetic anhydride to produce my novel compounds.

In general, the benzoxazotes which areused: as

I starting materials preparing my new 2-5:

acetanilidovinyl-benzoxazolesl maybe prepared by'ithe process; set-forth in application Serial No. 525,936; filed March'lafi', 194%. The followin examplesare-given bnwaylof, illustrating th i then reduced to form the corresponding amino-phenol procession producing such; startin materials;

Example 1,72,- .1, methyl firtertiaryebutyl-benz QXdZOlQ; i 1

, 2'-ni:.tro..-t-tertiary-hutyl-nhenot was. prepared bythe method described in 2,207,721 as follows; 45 grams of p-tertiary-butyl-nhenol. in 500.160.. of benzol was. nitratedwith; a; mixture. of. 128-0 on; of 7 nitric acid and 2.5 .0 cc. of water. The nitric) compound; was vacuum; distilled and s a boiling; p nt of. 1:36. at. 114; mm, The nitro-ter.tiary-butyl-phenol was. then reduced with alkaline sodium hydrosulfite; as follows:

2.0, grams of Z-nitro-d-tertiary-b uty1-phenol in 800 cc.v of 10% caustic. soda, solution was: heated to 82 C. and 75.0 grams of sodium hydrosulfitfe added. The clear alkaline solution was, acidified with dilute-acetic acid and the: White. crystalline plates. or 2-amino-I4 tertiarwbutylephenol precipitated. The compound melts at 1624; C. The yield obtained was, 16A grams. By h ating 44.7 grams of the dried aminoetertiary butyl plaenol with glacial acetic acid, or with an acetic acidacetic acid anhydride mixture containing cc. of each, 45.0 grams of Z-methyl-G-tertiary-butylbenzoxazolewas. obtained. The compound has a boiling point. of 137 C. at 16 mm,

I 7 CH3 oHtl Hi - C-C-Hi 2-nitro-4-cumyl-phenol was prepared by nitrating a mixture of 24.2 grams of p-cumylphenol in 40.0 cc. of benzol with a mixture of 12.8 cc. of 70% nitric acid and 25.6 cc. of water at '7-l0 C, The nitro compound had a boiling point of 145 C. at 15 mm. 2-amino-4-cumyl-phenol was obtained from the nitro compound by alkaline sodium hydrosulfite reduction. Z-methyl- G-cumyl-benzoxazole was then prepared by refluxing 8.2 grams of the 2-amino-4-cumylphenol with an acetic acid-acetic anhydride mixture containing 15 cc. of each, and finally dry distilling the reaction mixture. The 2-methyl- G-cumyl-benzoxazole obtained boils at 162 C. at

When heated with ethyl iodide, the substituted benzoxazole is converted'into the corresponding quaternary ammonium salt. 7 I

Example 3.2-methyl-6-' oamyl-benzoxazole.

2-nitro-4-isoamyl-phenol was prepared by nitrating a mixture of 37.4 grams of p-isoamylphenol in 150.0 cc. of benzene with a mixture of 22.6 cc. of 70% nitric acid and 22.6 cc. of water at -8 C. The nitro compound has a boiling point of 145-150 C. at 16 mm.

10.0 grams of the 2-nitro-4-isoamyl-phenol thus obtained was reduced with alkaline sodium hydrosulfite. 16 grams of the amino-compound so obtained was dry distilled from an acetic acidacetic anhydride mixture containing 25 cc. of each to form 2-methyl-6-isoamyl-benzoxazole. The compound has a boiling point of 270 C. at 760 mm. and 147 C. at 16 mm.

When heated with ethyl iodide, the substituted benzoxazole is converted into the corresponding quaternary ammonium salt.

The benzoxazoles obtained according to the above examples may be converted into other quaternary salts by heatingwith other suitable alkylating agents such as ethyl-p-toluenesulfonate, methyl sulfate, diethyl sulphate, or any other acid radical forming an alkyl-or aralkyl ester.

To form the 5-substituted secondary and tertiary alkyl and alkyl-aryl benzoxazoles, I proceed in the same manner as set forth in the above examples, except that I start with a 2-nitro-phenol .4 and the mixture was heated in an oil bath to 140 C. for about forty minutes. The reaction mixture was cooled and ethyl ether added to precipitate the 2-,8-acetanilidovinyl-benzoxazole. The reaction product was purified by erystalizing from dilute ethyl alcohol. The product was obtained in the form of colorless crystals, having a melting point of 210 C. and the probable formula given above.

Example 5.-2-p-acetanilidovinyl 6 cumylbenzoxazole ethiodide.

7 tainable by the process of Example 2 and diphenylformamidine in the proportions of 1 mol to 1 mol were reacted in the presence of acetic anhydride according to the process of Example 4. After purification a compound having the probable formula given above is obtained.

Example 6.2-p-acetanilidovinyl 6-isoamylbenzoxazole ethiodide.

which is substituted in the 5-position with a tertiary-butyl, a cumyl, or an isoamyl, or any other secondary or tertiary-alkyl or aryl-alkyl radical. The following examples will serve to illustrate the method of producing my new 2-,6-acetanilidovinyl benzoxazoles.

Example 4.-2 -,B acetanildovinyl-G-tertiarybutyl-benzoxazole-ethiodide.

3.4 gms. (0.01 mol) of 2-methy1-6-tertiarybutyl-benzoxazole ethiodide, which may be obtained according to Example 1, and 3.9 gms. of

diphenylformamidine (0.01 mol plus 100% excess) were dissolved in 15 cc; of acetic anhydride 2-methyl-fi-isoamyl-benzoxazole ethiodide, the product obtainable according to Example 3 and diphenylformamidine in. the ratio of 1 mol to 1 .7 mol were reacted in the presence of acetic anhydride according to the process recited in Example 4. After purification a compound having the formula indicated above is obtained.

In a similar manner the free secondary and i tertiary substituted benzoxazoles, instead of the quaternary ammonium salts, may be reacted in order to obtain the novel 2-fi-acetanilidovinylbenzoxazoles per se. To form the Z-p-acetanilidovinyl-benzoxazoles which are substituted by the secondary and tertiary alkyl and alkyl-aryl groups in the 5-position, I react the corresponding substituted benzoxazoles with diphenylformamidine in the presence of acetic anhydride in the same manner as set forth in the above examples.

The novel compounds may be condensed to form the new oxacarbocyanine dyes as disclosed in my co-pending application Serial No.- 525,935 filed March 10, 1944. In general the process of forming the dyes with my novel intermediate comprises condensing the 2-,8-acetanilidovinyl derivatives of the secondary and. tertiary substituted benzoxazoles with secondary and tertiary substituted Z-methyl benzoxazoles in the presence of pyridine, or any other suitable condensing agent.

I claim:

1. 2-p-acetanilidovinyl-6-cumyl benzoxazole and the quaternary ammonium salts thereof.

2; A process for preparing a benzoxazole which comprises reacting Z-methyl-G-cumyl-benzox- Name I Date Wilson July 6, 1943 Galloway July 16, 1940 Kendall Dec. 9, 1941 Schneider Sept. 19, 1939 FOREIGN PATENTS Country Date Germany Nov. 7, 1935 OTHER REFERENCES Chem. Abstracts, Vol. 26, page 705, citing: Bull. 00. Chim. (4), vol. 49, pp. 1213-1222 (1931).

Chem. Abstracts, Vol. 32, page 2119.

Certificate of Correction Patent No. 2,429,179. October 14, 1947.

ALFRED W. AN ISH It is hereby certified that the above numbered patent was erroneously issued to the inventor Alfred W. Anish, Whereas said patent should have been issued to Genera Aniline ct; Film Corporation, as assignee of the entire interest therein, as shown by the record of assignments in this Oifice; in the printed specification, column 1, line 48, strike out the word amine; column 4, line 1, for heated in read heated on; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 10th day of February, A. D. 1948.

THOMAS F. MURPHY,

Assistant Uommissioner of Patents. 

